Later circadian sleep timing, later weekday bedtimes, and shorter sleep duration are associated with insulin resistance in adolescents who have overweight or obesity, according to study results published in The Journal of Pediatrics.

In this cohort study, researchers recruited 31 adolescent patients (77% female, mean age 16.0 ± 1.4 years) with body mass index ≥90th percentile for age and sex from Children’s Hospital Colorado outpatient clinics between September 2014 and May 2017. All patients wore an actigraphy monitor to estimate sleep duration, timing, and characteristics for 1 week during the academic year, while also keeping a sleep diary reporting bedtimes and wake times. After 7 days, a 3-hour fasting oral glucose tolerance test was performed to assess insulin sensitivity on either a Thursday or a Friday to ensure results were consistent with a week of accumulated sleep debt. Following the glucose test, participants were exposed to dim-light conditions for the duration of an overnight stay at a Children’s Hospital Chicago research center; salivary melatonin samples were measured every 30 to 60 minutes from 5 PM to 12 PM the following day.

All participants obtained insufficient sleep on both weekday and weekend nights compared with the recommended 8 to 10 hours for this age group. On average, participants obtained 6.6 ± 0.96 hours of sleep time on weekday nights and 7.5 ± 0.88 hours of sleep time on weekend nights, with significantly longer sleep duration, more time in bed, and later sleep timing (bedtime, midpoint time, and wake time) on weekends vs weekdays. Compared with participants who obtained ≥6.6 hours of sleep/night (the median sleep duration), participants with <6.6 hours of sleep/night had significantly worse scores for insulin resistance (P =.02) and sensitivity (=.007). Significantly different area under the curve values were observed for insulin between the groups (=.03), indicating lower insulin measures throughout the oral glucose tolerance test for adolescents with ≥6.6 hours of sleep. There was no significant difference between groups for glucose levels.

Participants who spent more time in bed and asleep overall, and who had earlier bedtimes during the week, showed significantly better insulin sensitivity. Later circadian timing of sleep onset, indicated by later onset and offset of melatonin, was associated with worsened insulin sensitivity (P =.03).

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“Clinicians should consider assessment and treatment of sleep and circadian health, including sleep duration, time in bed, and sleep timing, when working with adolescents with overweight/obesity,” concluded the study investigators. “Future studies exploring the physiological mechanisms involved in the relationship between sleep and circadian health and insulin response are urgently needed and may inform novel prevention and intervention strategies for [insulin resistance] and [type 2 diabetes] for adolescents.”

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Simon SL, Behn CD, Cree-Green M, et al. Too late and not enough: School year sleep duration, timing, and circadian misalignment are associated with reduced insulin sensitivity in adolescents with overweight/obesity [published online November 19, 2018]. J Pediatr. doi:10.1016/j.jpeds.2018.10.027